The present invention concerns antennas intended to convert an alternating voltage into a microwave and vice versa and, more particularly, antennas of this type comprising a conductive element and a ground plane separated by a dielectric substrate. These antennas are also known as microstrip patch antennas. The invention may be used to emit and/or to receive GPS (Global Positioning System) signals and, furthermore, it may be incorporated in watches or in other horological products. The invention will thus be described in the context of this exemplary application. However, it will be understood that the invention is of course not limited to this application.
The miniaturization of antennas of the type described above is generally accomplished by using a substrate having a very high permitivity. This invariably implies the use of a ceramic substrate. The fabrication costs of such a substrate are often high.
In addition, miniaturized antennas of this type possess a very narrow bandwidth. Consequently, due to manufacturing tolerances, the design and construction of these antennas is a difficult task. The mechanical adjustment of the edges of the conductive element is a technique which has been used for a long time to obtain the desired resonance frequency of the antenna. Nevertheless, such a solution is both destructive and cumbersome.